Objectives

There is paucity of information on the antimicrobial susceptibility pattern of oral anaerobic bacteria. In this study, an attempt has been made to evaluate the antimicrobial susceptibility/resistance trend of oral Gram negative bacteria from Indian subjects.

Methods

Minimum inhibitory concentrations (MIC) of 304 isolates against twelve different antibiotics were determined using gradient diffusion MIC strips. The organisms were isolated and identified based on phenotypic characteristics and included Porphyromonas gingivalis, Prevotella species, Tannerella forsythia, Fusobacterium nucleatum, Aggregatibacter actinomycetemcoitans, Eickenella corrodens and Capnocytophaga species. For each antimicrobial agent, MIC₅₀ and MIC₉₀ were calculated and expressed.

Results

Resistance to azithromycin, clindamycin, and amoxicillin was observed in most of the anaerobic bacterial species studied. High degree of susceptibility was observed to amoxillin-clavulanic acid, doxycycline and moxifloxacin. A single strain of P. melaninogenica was resistant to moxifloxacin. The susceptibility pattern varied with cephalosporins among species. Ceftriaxone showed highest and cefazolin least efficacy among cephalosporins. All anaerobic bacteria tested were susceptible to metronidazole. Strains of T. forsythia were more resistant to several antibiotics than other anaerobic bacteria. All three species of capnophilic bacteria displayed high degree of resistance to metronidazole and significant resistance to amoxicillin, azithromycin, clindamycin, cefazolin and cefuroxime.

Conclusions

Amoxicillin-clavulanic acid, doxycycline, moxifloxacin and metronidazole appeared to be the most effective drugs against gram negative anaerobic bacteria. However, the MIC₅₀ and MIC₉₀ values against metronidazole were on the higher side of the normal indicating a potential for developing resistance.

中文翻译：

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印度受试者口腔革兰氏阴性厌氧菌的抗菌药物敏感性模式

目标

关于口腔厌氧菌的抗菌敏感性模式的信息很少。在这项研究中，已尝试评估来自印度受试者的口腔革兰氏阴性菌的抗菌敏感性/耐药性趋势。

方法

使用梯度扩散 MIC 试纸条测定 304 株分离株对 12 种不同抗生素的最低抑菌浓度 (MIC)。基于表型特征分离和鉴定生物体，包括牙龈卟啉单胞菌、普氏菌属、连翘单胞菌、具核梭杆菌、放线聚合杆菌、腐蚀埃肯菌和嗜二氧化碳嗜血杆菌属。对于每种抗微生物剂，计算并表达MIC ₅₀和MIC ₉₀。

结果

在研究的大多数厌氧菌种中观察到对阿奇霉素、克林霉素和阿莫西林的耐药性。观察到对阿莫西林-克拉维酸、多西环素和莫西沙星的高度敏感性。P. melaninogenica 的单一菌株对莫西沙星具有抗性。不同物种间头孢菌素的易感性模式不同。在头孢菌素中，头孢曲松的疗效最高，而头孢唑啉的疗效最低。所有测试的厌氧菌均对甲硝唑敏感。T. forsythia菌株比其他厌氧细菌对几种抗生素的抵抗力更强。三种嗜二氧化碳菌均对甲硝唑表现出高度耐药性，对阿莫西林、阿奇霉素、克林霉素、头孢唑啉和头孢呋辛均有显着耐药性。

结论

阿莫西林-克拉维酸、多西环素、莫西沙星和甲硝唑似乎是对抗革兰氏阴性厌氧菌最有效的药物。然而，对甲硝唑的 MIC ₅₀和 MIC ₉₀值高于正常值，表明可能产生耐药性。